1. Field of the Invention
The invention relates to an organic light emitting device. More particularly, the invention relates to an organic light emitting device with high light extraction efficiency.
2. Description of Related Art
The information and communication industries have become indispensable in our society thanks to the focused development of various portable communication and display products. As the flat panel display is one of the communication interfaces between human and an information device, development of the flat panel display is rather essential. The organic light emitting device has tremendous application potential to become the mainstream of the next generation flat panel display due to its advantages of self-luminescence, wide viewing angle, low power consumption, simple manufacturing process, low cost, low working temperature, high response speed, full-color display, and so forth.
Generally, the organic light emitting device is comprised of a first electrode layer located on a substrate, a second electrode layer, and an organic light emitting layer sandwiched between the two electrode layers. The substrate and the first electrode layer are often made of a light transmissive material, such that light generated by the organic light emitting layer can be emitted. However, a refractive index of the substrate is 1.4˜1.6 approximately, and a refractive index of the air is 1. Therefore, light emitted from the organic light emitting layer at a wide angle cannot be well transmitted from the substrate to the air. As such, light extraction efficiency of most organic light emitting devices simply reaches 15%˜20% approximately.